Yes, I've had several different types of tetras reproduce in my tank... and I wasn't trying... and yes, they survived. The priscellas and lemons had the best rate. I don't know "when" they spawned but all of a sudden I would start to see little groups of tinie-tiny "replicas" moving around (usually hiding within the leaves of my amazon sword). Most little ones I saw "appear" at once was probably about a dozen. When I switched to lemons I started with 7 in my 150 discus community tank... after a year I had just over 40 at one point. Had to give some away because I had so many. Then, they started reproducing all over again. While trying to go from canister to DIY sump I royally screwed something up and lost all lemons, a few discus, and discus stopped spawning for a long time. Sooo... right now I have 6 lemons and since the discus started spawning again then I might expect to start seeing baby lemons again. That said, seems that the discus eggs are having a lot more fungus problems than in the past... I never should have screwed with filtration... ah well.
I think if you look at my old thread in the planted section then you'll see some baby lemon and/or priscellas mixed in to some pictures. At just a few mm's they look just like parents practically.